There is still debate about whether Lowland Anoa (Bubalus depressicornis) and Mountain Anoa (Bubalus quarlesi) are distinct species (Burton et al. 2005). Two phenotypes of anoa, characterized by body size, hair texture, horn shape, and presumably body colours have been used by certain authors to justify the existence of two species. However, transitory morphs suggest that the real relationships are more complex, and hardly understood. Sulawesi is a rather small territory, so the speciation patterns of a large mammal pose a riddle to systematists. An enormous underlying variability (outward appearance, anatomy, chromosomes, proteins, DNA) has hitherto precluded a convincing classification, or has questioned the validity of an approach to group anoa diversity into clear, reproducible types. Pattern-based classifications of zoo and museum specimens, most of which are devoid of reliable information as to their origin within Sulawesi, have always suffered from the later discovery of phenotypes with new combinations of supposedly diagnostic species characters.

The "transitory populations" probably do not represent "hybrids" of two species, but various degrees of genetic introgression, or even primary clines of diverging evolutionary lineages, and they could perhaps differ in different regions of Sulawesi, depending on the degree of gene flow, and the characters affected. At the present stage of insight, every regional anoa population should be considered worthy of conservation. The management units should at least be based on known origins from within Sulawesi, rather than on taxonomic schemes, which in the past have often proved incomplete.

The English common names of the two species relate to a still uncertain altitudinal separation (Groves 1969), with the large form (Lowland Anoa) inhabiting low-lying areas and the smaller form (Mountain Anoa) living at higher elevations (Burton et al. 2005).

Justification:
This species is considered Endangered because its population is estimated to be less than 2,500 mature individuals, its rate of decline is believed to be greater than 20% over two generations (14 to 18 years), and no subpopulation is believed to number more than 250 mature individuals.

This species is endemic to Indonesia, where it is found only on Sulawesi and Buton Island off the southeast coast, with no records of either species of Anoas from other small neighbouring islands adjacent to Sulawesi (Burton et al. 2005), where it is found up to 1,000 m (G. Semiadi pers. comm. 2006). It remains uncertain whether the two putative species, Bubalus depressicornis and Bubalus quarlesi, are sympatric or parapatric in their distribution (Burton et al. 2005). Across the island, local distribution of anoa species remains unclear, as they may occur in forest patches at different altitudes or sympatrically (Burton et al. 2005). Records of skulls and morphological descriptions of this species suggest it is present in the northern peninsular, as far east as the Bogani Nani-Wartabone National Park. It is also found across the central region and ranging to the tip of the eastern and southeastern peninsulars, but no longer present in the south peninsular. The lowland anoa is also present in the central and north of Buton Island (Burton et al. 2005).

Historically, anoa of one species or other were present throughout the majority of the island’s forests (Weber 1890, Sarasin and Sarasin 1901, Mohr 1921, Harper 1945, Groves 1969, Burton et al. 2005).

There are to few data exist to accurately quantify the species' current abundance, nevertheless, they still appear to be distributed relatively widely within their known historical range on Sulawesi. There have been declines of this species throughout Sulawesi, especially in the southern and northeastern peninsulas, with the decline attributed to hunting for meat and habitat loss (Burton et al. 2005). The range is extremely fragmented, especially in the southern, northeastern and the south of the southeastern peninsulas of the island (Burton et al. 2005, B. Mannullang pers. comm. 2006). These declines probably began at the turn of the nineteenth century, with an increased decline rate from the 1980 to 2005 period (circa three generations), precipitously in some areas. The population size is unknown because there have been no island-wide surveys to estimate this, even for the largest populations. Estimating the population size is further complicated by the uncertain distribution of the two Anoa species. It is thought that there are less than 2,500 mature individuals. Most populations are becoming rapidly fragmented, suggesting that conservation of viable populations may soon require management of subpopulations (Burton et al. 2005). It is thought no subpopulation exceeds 250 mature individuals. The threats to this species, and thus the declines, are more serious for this species than for the Mountain Anoa.

The Lowland Anoa populations in small reserves (e.g., Tanjung Amolengu Wildlife Reserve) and other forest fragments are threatened with local extinction. Even the populations in large protected areas and other large forest blocks are reported to be in decline as a result of heavy hunting pressure. O'Brien and Kinnaird (1996) report a 50 to 95% decline of this species in Tangkoko Nature Reserve in Northern Sulawesi in a 10-year period, with more recent surveys suggesting it is now locally extinct. The rate of population decline across their range is thought to be 20% over two generations (generation length of 7 to 9 years). The species’ ecology was studied recently in the Tanjung Peropa and Tanjung Amolengo Wildlife Reserves in southeastern Sulawesi.

There is very little is known about the ecology and life history of the Anoas (Burton et al. 2005). Overall population densities were estimated to be 0.9 and 1.1 anoas/km² in Tanjung Peropa and Tanjung Amolengo Wildlife Reserves, southeast Sulawesi, respectively (Mustari 2003). This species is found in both primary and secondary lowland forest, as well as swamp and mangrove forest (A. Priyono and G. Semiadi pers. comm. 2006, Mustari 2003). Riverine and lowland forests were preferred by anoa compared to rocky-cliffs forest in Tanjung Peropa Wildlife Reserve due to the availability of water sources, known food plants and fruit-bearing trees (Mustari 2003). In the past the species was reportedly common along coasts. Lowland Anoa are also found at high elevations in mountainous areas. Like other wild buffalo, Anoas wallow and bathe in pools of water and/or mud. It is probable that mineral springs or licks are also required, although Anoa are reported to drink seawater, which might fulfil their mineral needs in areas without licks or springs.

The species is solitary and is a browser, feeding on vegetation (Whitten et al. 1987, Foead 1992). The typical life span in captivity is reported to be 20 to 30 years, with age at sexual maturity at 2 to 3 years old (in captivity), with typically one offspring per year (NRC, 1983; Jahja, 1987), though in wild conditions this may be less.

Land conversion to agriculture and hunting, mainly for food, are the two major threats to this species (Burton et al. 2005), as well as gold mining and other activities related to the collection of non-timber forest product (A. Priyono pers. comm. 2006). Recent reports indicate that hunting is by far the more serious threat. International trade in live animals or body parts is not thought to present a serious threat.

The species is listed on CITES Appendix I and fully protected under Indonesian law (Jahja 1987). Lowland Anoa occur in a number of protected areas (Burton et al. 2005). There are several key protected areas thought to hold significant populations of this species, including Lore Lindu National Park, Bogani Nani-Wartabone National Park, and Tanjung Peropa Nature Reserve on Sulawesi (Burton et al. 2005), as well as Lambu Sango Wildlife Reserve on Buton Island (Burton 2001). There is an ongoing status survey, as well as genetic and morphological research that aims to clarify the confusion that surrounds anoa systematics. A number of Lowland Anoa are in captivity, but the breeding program has been greatly hindered by the difficulties of assigning captive anoa to appropriate taxa. The captive population doubled in size in the 1990s, with around 125 individuals in zoos as of 1998. Of these, a small number are thought to be Mountain Anoa, although the taxonomic status of most individuals remains unconfirmed (Nötzold 1999).

According to Burton et al. (2005) this species requires the following conservation actions: (1) protection from hunting, (2) prevention of habitat loss at key sites, (3) complete genetic studies to better determine the taxonomy of this species, and (4) determination of the status of remaining populations. This species, as it is confined mainly to lowland areas, requires well established protected areas with protection from hunting a major priority. Law enforcement combined with education should be employed to reduce hunting pressure.

Burton, J. A. 2001. The Anoa 2000 Conservation Project. Field Report: Systematics and Conservation of Large Mammals in South East Sulawesi (Sulawesi Tenggara), with Notes on North and Central Sulawesi. Unpublished Report.

Scott, P. 1965. Section XIII. Preliminary List of Rare Mammals and Birds. The Launching of a New Ark. First Report of the President and Trustees of the World Wildlife Fund. An International Foundation for saving the world's wildlife and wild places 1961-1964, pp. 15-207. Collins, London, UK.